The International Agency for Research on Cancer (“IARC”), the specialized cancer agency of the World Health Organization, garnered attention in June 2016 when it deemed coffee “not classifiable” in terms of whether it increases human cancer risk. Though this new category may sound ambivalent, it was quite notable because IARC had previously classified coffee as “possibly carcinogenic.” When IARC classifies an agent as carcinogenic, probably carcinogenic, or even possibly carcinogenic, it often triggers a series of burdensome labeling obligations and gives rise to a wave of litigation for companies whose products contain the substance, even in trace amounts. Just what are IARC’s classifications, what are the significant obligations and litigation risks that classification by IARC as a (possible, probable) carcinogen may set in motion for consumer product companies, and what effect does a reversal by IARC have on those obligations and litigation risks?

IARC and its Carcinogenicity Classifications. IARC regularly issues monographs that identify environmental factors that can increase human cancer risk. IARC has evaluated more than 900 agents since 1971, ranging from chemical compounds to medications, from health conditions to foods. It selects agents for evaluation based on two main criteria: (1) evidence of human exposure and (2) some evidence or suspicion of carcinogenicity, including that an agent has physical or biological characteristics that are similar to another suspected carcinogen. Interdisciplinary working groups of scientists then review published studies, including both animal and human studies, and evaluate the weight of the evidence about whether a particular agent can increase cancer risk. The agent is then categorized as:

Group 1: The agent is carcinogenic to humans, which is used when there is “sufficient evidence of carcinogenicity in humans” or, exceptionally, when “evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent acts through a relevant mechanism of carcinogenicity.”

Group 2A: The agent is probably carcinogenic to humans, which is used mostly when there is “limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals.”

Group 2B: The agent is possibly carcinogenic to humans, which is used mostly when there is “limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals.” However, agents can be placed in this category even when there is “inadequate evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals” if there is strong mechanistic evidence.

Group 3: Based on currently existing studies, the agent is not classifiable as to its carcinogenicity to humans, which is used mostly when “evidence of carcinogenicity is inadequate in humans and inadequate or limited in experimental animals.” This category is used for agents that do not fall into any other group. It often means that further research is needed, and IARC cautions that it is not a determination of safety.

Group 4: The agent is “probably not carcinogenic to humans,” which is used when there is “evidence suggesting lack of carcinogenicity in humans and in experimental animals,” or in some instances where there is inadequate evidence as to humans but “evidence suggesting lack of carcinogenicity in experimental animals, consistently and strongly supported by a broad range of mechanistic and other relevant data.”

See International Agency for Research on Cancer, World Health Organization, Centre international de recherche sur le cancer (Lyon), & Kongress, IARC monographs on the evaluation of carcinogenic risks to humans, Preamble (September 2015), available here.

IARC’s Carcinogenicity Determinations Often Find Their Way into State Consumer Protection Laws and Trigger Lawsuits. Categorization of a product or substance found in it as carcinogenic, probably carcinogenic, or even possibly carcinogenic can have a range of impacts on companies offering consumer products, from requiring new warnings on products to fresh lawsuits.

First, many states incorporate IARC’s determinations into their consumer protection statutes, triggering warning and labeling requirements or even bans on the sale or purchase of the products. For example, several states have targeted art supplies, requiring warnings and imposing additional labeling requirements when they contain substances identified by IARC as carcinogenic or even possibly carcinogenic. In some states, the sale to or purchase of those art materials by schools is even banned. See, e.g., Conn. Gen. Stat. §§ 10-217c through 10-217e (Connecticut); 105 Ill. Comp. Stat. §§ 135/3, 135/5, 135/6 (Illinois); Or. Rev. Stat. §§ 453.205, 453.235, 453.245 (Oregon); Tenn. Code Ann. §§ 68-131-303, 68-131-304 (Tennessee).

The elephant in the room and most wide-ranging of these state laws is California’s Proposition 65, the California Safe Drinking Water and Toxic Enforcement Act of 1986, under which an IARC classification often leads to the requirement for an additional, prominent warning label. Under Proposition 65, the State of California maintains and regularly updates a list of chemicals known to cause cancer (the “Proposition 65 List”). Technically termed a list of “chemicals,” it also includes substances like “Wood Dust,” “Marijuana Smoke,” and “Salted Fish, Chinese Style.” The current Proposition 65 List is available here. An assessment of even possible carcinogenicity by IARC starts the “authoritative bodies” mechanism for listing and also incorporates the substance into the Labor Code, prompting a review and public comment period before the substances are added to the Proposition 65 List. See Cal. Labor Code § 6382(b)(1); Cal. Code Regs. §§ 25904, 25306; see also Cal. Office of Envt’l Health Hazard Assessment’s (OEHHA) diagrams of listing processes, available here and here.

If a substance is added to the Proposition 65 List, that addition triggers the requirement for companies doing business in California to provide a “clear and reasonable” warning about the cancer risk before exposing anyone to the listed substance. Cal. Health & Safety Code § 25249.6. Often, this warning is through the product label or a menu notice. An example of a common and state-endorsed warning for products that contain a carcinogen is “WARNING: This product contains a chemical known to the state of California to cause cancer.” Unless a product fits within an exception, such as when the listed compound is a naturally occurring part of a food or when the company can show the substance is present below a “no significant risk level,” a company must comply with the warning requirement within one year from the date of listing. See Cal. Health & Safety Code § 25249.10 (exceptions). However, the warning requirements are slated to become more onerous with the adoption of new regulations that impose additional requirements and go into effect in 2018. See 37-Z Cal. Regulatory Notice Reg. 1650-51 (Sept. 9, 2016) and revised regulations and explanatory materials from the California OEHHA, available here. Failure to provide the requisite warning – or to remove the offending compound from the product in lieu of providing a warning – can lead to civil penalties of up to $2,500 a day. Cal. Health & Safety Code § 25249.7(b)(1). The California Attorney General, district attorneys, and city attorneys in larger cities can all bring enforcement actions. Cal. Health & Safety Code § 25249.7(c).

Proposition 65 also includes a private plaintiff provision, incentivizing citizens and plaintiffs’ lawyers to identify products that lack a warning label. See Cal. Health & Safety Code § 25249.7(d). As a result, companies that fail to relabel products sold in California can face litigation seeking civil penalties and the accompanying attorney’s fees that in many ways drive these suits. In some instances, these suits are based not on the product or its ingredients, but on trace contaminants, leading to expert-heavy litigation that delves into the often difficult question of whether the contaminants are present at a level that poses any risk. For example, dozens of coffee sellers, including major coffeehouse chains, were sued for failing to warn consumers that the coffee – which itself was not included on the Proposition 65 List despite its IARC Group 2B “possibly carcinogenic” classification of coffee and for which no warning would have been required because it fit into an exception as a naturally occurring part of the food – allegedly posed a cancer risk because the roasting process led to trace amounts of acrylamide, which was on the Proposition 65 List. See Complaint, Council for Education and Research on Toxics v. Brad Berry Co. Ltd. et al., Case No. BC461182 (Superior Court of the State of California, County of Los Angeles May 9, 2011), available here.

Second, even if no state consumer protection statute requires a warning on a particular product, companies may still face consumer suits alleging that IARC’s classification bars the use of other terms on packaging or in advertising. For example, in March 2015, IARC classified glyphosate, an herbicide, as a Group 2A “probable” human carcinogen. Glyphosate is the active ingredient in Roundup, and it has been identified in residual amounts in products containing oats treated with the common herbicide product. As of the date of this post, glyphosate has been under consideration for addition to California’ Proposition 65 List, but it has not yet been added. See California Envt’l Protection Agency, OEHHA, Notice of Chemicals Listed Effective May 20, 2016 as Known to the State of California to Cause Cancer: Tetrachlorvinphos, Parathion, and Malathion (May 20, 2016), available here.Nonetheless, shortly after IARC’s listing – before any specific requirement to warn consumers about the presence of glyphosate in products – several food manufacturers found themselves facing false advertising claims based on the alleged presence of glyphosate in their oat-based breakfast and snack food products. According to the plaintiffs, the foods are harmful and chemical-laden because they contain glyphosate, and therefore “healthy” or “natural” labeling and marketing is false, misleading, and violates state consumer protection laws. See Complaint, Organic Consumers Ass’n v. General Mills, Inc., No. 2016CA6309 (D.C. Super. Aug. 24, 2016) (D.C. Super.), 2016 WL 4487949 (challenging use of claims like “Made with 100% Natural Whole Grain Oats” and “healthy” on a variety of Nature Valley brand products, including granola bars, biscuits and breakfast biscuits, oatmeal squares, oatmeal bars, and oatmeal bistro cups as violations of the District of Columbia Consumer Protection Procedures Act); Complaint, Wu v. Post Foods, LLC, No. 16-cv-3494 (N.D. Cal. June 22, 2016), 2016 WL 3458149 (claiming “100% Natural Whole Grain Wheat” and “Natural Source of Fiber” on Shredded Wheat products and “natural” brand image violated the California Legal Remedies Act, False Advertising Law, and Unfair Competition Law); Complaint, Gibson v. Quaker Oats Co., No. 16-cv-4853 (N.D. Ill. May 2, 2016), 2016 WL 1730276 (challenging claims including “Natural,” “100% Natural Whole Grain,” and “Heart Healthy” on Quaker Oats Old-Fashioned, Quaker Oats Quick 1-Minute, and Quaker Steel Cut Oats and a brand image that is “Natural, ‘Green,’ and Environmentally Conscious” under the Illinois Food, Drug and Cosmetic Act and Illinois Consumer Fraud and Deceptive Business Practices Act); Complaint, Wheeler v. Quaker Oats Co., No. 2016CH06075 (Ill. Cir. Ct. Cook County May 2, 2016), 2016 WL 2341998 (same); Complaint, Daly v. Quaker Oats Co., No. 16-cv-2155 (E.D.N.Y. Apr. 29, 2016), 2016 WL 1732634 (challenging same claims as in Gibson and Wheeler under New York Business Law § 349: Mislabeling and Failure to Warn and § 350).

Third, classification of a substance in a consumer product as a carcinogen – whether by IARC, a state agency, or another prominent body like the National Toxicology Program – also may tip off a wave of traditional products liability suits. These suits sometimes seek medical monitoring to address the alleged risk of developing cancer in the future, particularly where exposure levels are low. By way of example, 4-Methylimidazole, known as “4-MEI,” is found in caramel colors and used in many food products. California added 4-MEI to the Proposition 65 List in 2011, and IARC classified 4-MEI as Group 2B possibly carcinogenic in 2013. Proposition 65 List, available here; International Agency for Research on Cancer, World Health Organization, Centre international de recherche sur le cancer (Lyon), & Kongress, Some chemicals present in industrial and consumer products, food and drinking-water,IARC monographs on the evaluation of carcinogenic risks to humans, 447-457 (2013), available here. Nine putative class actions were then filed against PepsiCo, many of them focused on labeling issues and alleging that various beverages contained 4-MEI at unhealthy levels that precluded certain labeling claims and required warnings. Riva v. PepsiCo, Inc., 82 F. Supp. 3d 1045, 1049 (N.D. Cal. 2015). However, the named plaintiffs in the Riva action went beyond whether the products had appropriate labeling and warnings, and they brought personal injury claims for negligence, strict liability based on defective design, and strict liability based on failure to warn. Rather than allege an existing injury, they claimed an increased risk of cancer and sought medical monitoring. Id. at 1049-50.

A “Reversal” by IARC Rarely Brings a Quick End to the Obligations and Risks that the Original Cancer Classification Set in Motion, But It Improves the Odds. After deeming an agent as (possibly, probably) carcinogenic, in some instances IARC later changes course and reclassifies the agent as less likely to be carcinogenic than it had previously found. As noted at the top of this post, in 1991, IARC had grouped coffee as a Group 2B possible carcinogen. In June 2016, after further evaluation including newer studies, IARC then announced that coffee is in Group 3, “not classifiable.” What happens when IARC reverses course and later determines that an agent actually is not classifiable, or even probably not carcinogenic?

In terms of warning obligations, California’s Proposition 65 expressly addresses the possibility that an IARC reversal could merit removing the onus of warning consumers about the risk of cancer. However, that relief is not automatic. Instead, after the authoritative body changes its assessment and no longer identifies a substance as causing cancer, the substance will be reevaluated. If there is another basis for listing the substance, the substance may simply be listed with that alternative basis and remain on the Proposition 65 List; if not, the substance will be referred to California’s Carcinogen Identification Committee for a further evaluation that incorporates literature reviews and public comment. See Diagram Reconsideration of Chemicals Listed via the Authoritative Bodies (AB) Mechanism; Title 27, Cal. Code Regs., section 25306*, available here; Diagram Reconsideration of Chemicals Identified Via Labor Code section 6382(b)(1) and (d); Health and Safety Code section 25249.8(a); Title 27, Cal Code of Regs., section 2590, available here; and Diagram Listing via the State’s Qualified Experts (SQEs) Mechanism; Health and Safety Code §25249.8(b) and Title 27, Cal. Code Regs., section 25305*, available here. During that reconsideration, the substance remains on the list, with all related obligations in force. Cal. Code Regs. tit. 27 § 25306(j). While a course change by IARC does not mean an automatic end to listing and obligations under Proposition 65, California has delisted over a dozen “cancerous” substances over the years. See Cal. Envt’l Protection Agency, OEHHA, Chemicals Known to the State to Cause Cancer or Reproductive Toxicity (Sept. 30, 2016), available here (listing both currently-listed agents and delisted agents). Beyond waiting for delisting, a company impacted by the warning requirement also could seek a declaratory judgment that its product poses no significant risk of cancer in humans and, as a result, that it need not provide a Proposition 65 carcinogenicity warning. See, e.g., Baxter Healthcare Corp. v. Denton, 120 Cal. App. 4th 333, 15 Cal. Rptr. 3d 430 (Cal. App. 3rd Dist. 2004) (affirming judgment that Bayer had no obligation to provide Proposition 65 warnings and relieving it of obligation to include warning, even though substance was still on the Proposition 65 List).

For other consumer protection suits and traditional product liability suits, an IARC “downgrade” is helpful, but often not a silver bullet that brings suits to a prompt conclusion and forecloses future litigation. First, none of IARC’s classifications is a definitive conclusion that an agent is not carcinogenic. IARC cautions that an evaluation in Group 3, “not classifiable as to . . . carcinogenicity in humans,” “is not a determination of non-carcinogenicity or overall safety. It often means that further research is needed, especially when exposures are widespread or the cancer data are consistent with differing interpretations.” See International Agency for Research on Cancer, World Health Organization, Centre international de recherche sur le cancer (Lyon), & Kongress, IARC monographs on the evaluation of carcinogenic risks to humans, Preamble (September 2015), available here. Group 4 is “probably not carcinogenic to humans,” and used for agents for which “there is evidence suggesting lack of carcinogenicity in humans and in experimental animals.” Id. Second, IARC’s evaluations are based only on existing studies and how currently-known mechanisms of carcinogenicity operate in humans and animal species. A later study that finds a link between the agent and any type of cancer can reignite the debate.

In many cases, even with the benefit of being downgraded to “not classifiable” or “probably not carcinogenic,” defendants may still be left with the onerous undertaking of trying to prove a negative and the need to muster substantial scientific evidence to draw the case to a conclusion. Cf. Baxter Healthcare, 120 Cal. App. 4th at 349-40, 15 Cal. Rptr. 3d at 438-39 (after IARC reclassification of chemical plasticizer di(2–ethylhexyl)phthalate (DEHP) in its medical devises to “not classifiable” Group 3, still needing to prove that DEHP does not pose a significant risk of cancer by providing significant scientific evidence, including evidence regarding the mechanism of carcinogenicity for the agent in animals versus humans). In product liability cases, this means showing that the product did not cause the plaintiff’s cancer as a matter of general or specific causation, or, in the case of medical monitoring actions, that it does not pose a future cancer risk. In many suits claiming false and misleading labeling and advertising, defendants will be left to rebut plaintiffs’ claims that the products pose a risk of cancer and that any such risk makes health-related or natural claims false or misleading.

That is not to say that IARC’s conclusion that an agent is not classifiable or probably not carcinogenic carries no weight. It is particularly powerful when a plaintiff depends on little more than speculation and fails to put forth any reliable scientific evidence of causation, and it offers the court an authoritative basis to cite in dismissing an action. See, e.g., D'Agostino v. Prudential Ins. Co., No. A-5912-09T1, 2012 WL 3022140, at *5 (N.J. Super. Ct. App. Div. July 25, 2012) (affirming summary judgment in product liability suit against occupational exposure plaintiff whose expert offered limited basis for conclusion that cleaning products caused plaintiffs’ cancer and giving significant weight to fact that OSHA, NTP, and IARC did not list the products as carcinogens).

Conclusion. When IARC brands an agent as (possibly, probably) carcinogenic, it often sets in motion a chain of events that results in additional warnings on products and makes conditions ripe for a wave of new lawsuits. As the recent coffee and oat-based food product cases show, companies looking to limit their risks must be mindful not just of the ingredients listed in their products, but also any potential contaminants that may accumulate during the growth of those ingredients and processing. Even if IARC later reverses course, announcing that a substance is probably not carcinogenic or that the evidence is not adequate to classify it, that new determination does not stop the ball from rolling. Companies can expect a potentially long and uncertain wait before they are relieved on their obligation to warn about the cancer risk in California, and they must remain prepared to actively defend any related suits where the plaintiffs put forth their own scientific evidence.